The use of cooperating locking lugs on safety closures and containers to prevent children from gaining access to the contents of the container is well known in the prior art. Drugs, corrosive products, and antifreeze are examples of substances that are commonly packaged in containers or bottles having child-resistant or safety closures. The closures and their complementary containers are designed to allow the user to open the container without allowing a child to open the same.
An example of a child resistant closure and container is a push-and-turn system which is typically used for pill containers. This system requires that the closure or cap for the pill container be pushed axially downwardly and rotated at the same time. These containers are typical a two-piece, ramp and lug design. Essentially, the closure comprises an inner cap and an outer cap which are rotatably attached to one another. A plurality of lugs on one cap project towards a plurality of corresponding ramps on the opposite cap. Generally, the ramps and lugs engage each other when turned in a fastening direction such that the two caps turn in tandem. However, when the cap is merely rotated in an “unfastening” direction, the lugs tend to slide over the ramps. The outer cap turns freely from the inner cap, and the inner cap remains fastened to the container. In order to open the cap, the outer cap must be pushed downward in order to counteract the tendency of the lugs to slide over the ramps while the cap is being turned.
Another safety closure found in the prior art has bayonet type closures in which one of the closure and the container has a set of bayonet lugs and the other has a set of mating lugs so that it is necessary to urge the closure toward the container while applying a rotative force in order to disengage the bayonet lugs from the mating lugs to remove the closure from the container.
A typical configuration of the bayonet type closures found in the prior art are such that they have lugs or other features in the cap or closure that have a lug top surface forming an angle near 90° with an inner annular surface of the closure. This lug top surface cooperates with a bayonet lug having a lug receiving notch where the lug receiving notch has a top surface forming an angle near 90° with an outer surface of the container neck. This “square” cooperation retains the closure on the container by countering an axial force on the closure.
This “square” configuration found in the prior art creates costly and inefficient manufacturing problems. In the injection molding process the closure is axially removed from a mold core. In order to accomplish this removal, a collapsible mold core is typically used or alternatively holes are placed in the top wall of the closure to remove a portion of the mold which forms the lug top wall. This provides channels in the mold core for the closure lugs thus enabling axial removal of the closure from the mold core.